Wireless local area networks (WLANs) conforming to specifications in the Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 family typically involve a basic service set (BSS) managed by a device acting in the role of an access point (AP). Typically, the AP is connected through a gateway to a wide area network (WAN), such as the Internet. Since a given AP has a limited range, a mobile device that is associated with one AP, a source AP, may need to disassociate from that AP when moving out of range and form an association with a new AP, a target AP, providing coverage in the current location of the mobile device. The process of moving from source AP to target AP is known as roaming.
Connection of the mobile device to the WAN through an AP involves communications at the network layer (layer 3) of the Open Systems Interconnection (OSI) model and requires that the mobile device have a valid network address. In the context of communications over the Internet, the mobile device employs an internet protocol (IP) address that is assigned to it using the dynamic host configuration protocol (DHCP).
When roaming from the source AP to the target AP, the current IP address assigned to the mobile device remains valid when the source AP and the target AP are connected to the WAN through the same gateway. Many enterprise level network deployments utilize configurations that involve multiple APs sharing the same service set identifier (SSID) that are connected through a common gateway. Accordingly, the mobile device may assume a target AP having the same SSID as the source AP share the same gateway. If so, the IP address for a mobile device roaming between such APs remains valid and communications with the WAN are substantially uninterrupted when moving from the source AP to the target AP. As a result, conventional roaming processes may assume that a source AP and a target AP sharing an SSID are connected to the WAN through a common gateway and provide no mechanism for renewing the IP address of a roaming device.
However, when the source AP and the target AP are connected to different gateways, the IP address of the mobile device may not remain valid following a roaming event and layer 3 connectivity may be disrupted. Accordingly, it would be desirable to provide improved roaming performance and minimize disruptions in connectivity. The systems and methods of this disclosure provide a roaming process between a source AP and a target AP having different gateways that rapidly restores network connectivity to satisfy these and other goals.